1. Field of the Invention
This invention relates to a tamperproof capsule. More specifically, the invention relates to a self-locking hard gelatin capsule for containing a unit dosage of medication, vitamin, pain suppressant or the like.
2. Description of the Prior Art
It is a common accepted practice to enclose or encapsulate a dosage of medication, vitamins, pain killer or the like, whether the substance be powdered, granulated or pelletized, in a hard gelatin tubular or cylindrical capsule. These capsules are usually concentric, cylindrical structures with closed ends and telescope together, thus enclosing the desired amount of material. As such, they are subject to being easily disassembled and reassembled, thus generally they are not tamperproof.
In U.S. Pat. No. 3,173,380 a separation-resistant capsule is disclosed which involves a series of inwardly raised so-called land surfaces circumferentially separated by shallow inwardly open depressions or grooves on the domed end of the outer cylindrical cap of a conventional capsule. As this cap is compressed over the other cylindrical body portion of the capsule, the land and grooves tend to distort the top of the inner cylinder, thus gripping the capsule body. In this manner, the capsule will tend to resist separation but is not totally self-locking and is not fully tamperproof. In U.S. Pat. No. 3,927,193, this same gripping engagement is again disclosed and an additional sealing band is proposed at the external junction of the telescoping concentric walls. While, in U.S. Pat. No. 4,040,536 a hard gelatin capsule having concentric cylindrical body and cap members that telescope and supposedly lock is disclosed. Again, a frictional lock is achieved because of a plurality of small axially oriented indentions inwardly directed about a circumferential ring at the top of the outer capsule member, such that a frictional resistance is created on the open end of the cylindrical body member telescopically inserted into the cap member. However to the best of the present inventor's knowledge, none of the tamper resistant capsules proposed in the prior art are truly self-locking in the sense that once assembled, the capsule must be physically broken into order to disassemble.